Authorities in northern France say they are questioning two men about last year's train bombings in Madrid.
Officials say the men, a father and son, were taken in Tuesday in the northern town of Wervicq, near the Belgian border.
Authorities have not said what link, if any, the men have to the March 2004 Madrid bombings that killed 191 people and injured nearly 2,000 others.
A group claiming affiliation with al-Qaida took responsibility for the attack.
Spain has detained about 30 people in connection with the bombings.
Some information for this report provided by Reuters and AP.